Perhaps you should try some spelling variations:
sach thu » sach thue, sach thieu, sach tham
nam thuc » nam thuoc, am thuc, nam thu
vat dung » van dung, va dung, viet dung
dung doi » huong doi, dung tai, dung co
sach ty » sach tu, xach tay, sach hay
qua nam » quan nam, cua nam, quang nam
doi cua » dai cua, hoi cua
cua tre » cua te, cuu tre, cua triet
x hoi » xa hoi, o hoi, x ho

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: su ((((sach ty) OR (sach thu))) or (sach y)) nang x hoi. hieu qua nam thuc vat dung doi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((((sach ty) OR (sach thu))) OR (sach y)) nang x hoi. hieu qua nam thuc vat dung doi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((((sach ty) OR (sach thu))) or (sach y)) nang x hoi. hieu qua nam thuc vat dung doi cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((((sach ty) OR (sach thu))) or (sach y)) nang x hoi. hieu qua nam thuc vat dung doi cua tre*.